Anaplastic Lymphoma Kinase (ALK) is a cell membrane-spanning receptor tyrosine kinase, which belongs to the insulin receptor subfamily. The most abundant expression of ALK occurs in the neonatal brain, suggesting a possible role for ALK in brain development (Duyster, J. et al., Oncogene, 2001, 20, 5623-5637).
ALK is also implicated in the progression of certain tumors. For example, approximately sixty percent of anaplastic large cell lymphomas (ALCL) are associated with a chromosome mutation that generates a fusion protein consisting of nucleophosmin (NPM) and the intracellular domain of ALK. (Armitage, J. O. et al., Cancer: Principle and Practice of Oncology, 6th edition, 2001, 2256-2316; Kutok J. L. & Aster J. C., J. Clin. Oncol., 2002, 20, 3691-3702). This mutant protein, NPM-ALK, possesses a constitutively active tyrosine kinase domain that is responsible for its oncogenic property through activation of downstream effectors. (Falini, B. et al., Blood, 1999, 94, 3509-3515; Morris, S. W. et al., Brit. J. Haematol., 2001, 113, 275-295; Duyster et al.; Kutok & Aster). In addition, the transforming EML4-ALK fusion gene has been identified in non-small-cell lung cancer (NSCLC) patients (Soda, M., et al., Nature, 2007, 448, 561-566) and represents another in a list of ALK fusion proteins that are promising targets for ALK inhibitor therapy. Experimental data have demonstrated that the aberrant expression of constitutively active ALK is directly implicated in the pathogenesis of ALCL and that inhibition of ALK can markedly impair the growth of ALK+ lymphoma cells (Kuefer, Mu et al. Blood, 1997, 90, 2901-2910; Bai, R. Y. et al., Mol. Cell. Biol., 1998, 18, 6951-6961; Bai, R. Y. et al., Blood, 2000, 96, 4319-4327; Ergin, M. et al., Exp. Hematol., 2001, 29, 1082-1090; Slupianek, A. et al., Cancer Res., 2001, 61, 2194-2199; Turturro, F. et al., Clin. Cancer Res., 2002, 8, 240-245). The constitutively activated chimeric ALK has also been demonstrated in about 60% of inflammatory myofibroblastic tumors (IMTs), a slow-growing sarcoma that mainly affects children and young adults. (Lawrence, B. et al., Am. J. Pathol., 2000, 157, 377-384; Duyster et al.).
In addition, ALK and its putative ligand, pleiotrophin, are overexpressed in human glioblastomas (Stoica, G. et al., J. Biol. Chem., 2001, 276, 16772-16779). In mouse studies, depletion of ALK reduced glioblastoma tumor growth and prolonged animal survival (Powers, C. et al., J. Biol. Chem., 2002, 277, 14153-14158; Mentlein, R. et al, J. Neurochem., 2002, 83, 747-753).
An ALK inhibitor would be expected to either permit durable cures when combined with current chemotherapy for ALCL, IMT, proliferative disorders, glioblastoma and possible other solid tumors, or, as a single therapeutic agent, could be used in a maintenance role to prevent cancer recurrence in those patients. Various ALK inhibitors have been reported, such as indazoloisoquinolines (WO 2005/009389), thiazole amides and oxazole amides (WO 2005/097765), pyrrolopyrimidines (WO 2005080393), and pyrimidinediamines (WO 2005/016894).
The Janus kinases (JAKs) are a family of kinases of which there are four in mammals (JAK1, JAK2, JAK3 and TYK2) integral in signaling from extracellular cytokines, including the interleukins, interferons, as well as numerous hormones (Aringer, M., et al., Life Sci, 1999. 64(24): p. 2173-86; Briscoe, J., et al., Philos Trans R Soc Lond B Biol Sci, 1996. 351(1336): p. 167-71; Ihle, J. N., Semin Immunol, 1995. 7(4): p. 247-54; Ihle, J. N., Philos Trans R Soc Lond B Biol Sci, 1996. 351(1336): p. 159-66; Firmbach-Kraft, I., et al., Oncogene, 1990. 5(9): p. 1329-36; Harpur, A. G., et al., Oncogene, 1992. 7(7): p. 1347-53; Rane, S. G. and E. P. Reddy, Oncogene, 1994. 9(8): p. 2415-23; Wilks, A. F., Methods Enzymol, 1991. 200: p. 533-46). These non-receptor tyrosine kinases associate with various cytokine receptors and act to transduce the signal from extracellular ligand-receptor binding into the cytoplasm, by phosphorylating STAT (signal transducer and activator of transcription) molecules, which then enter the nucleus and direct transcription of various target genes involved in growth and proliferation (Briscoe, J., et al.; Ihle, J. N. (1995); Ihle, J. N. (1996); Rawlings, J. S., K. M. Rosier and D. A. Harrison, J Cell Sci, 2004. 117(Pt 8): p. 1281-3.). The importance of these kinases in cellular survival is made evident by the fact that the loss of JAKs is often accompanied by immunodeficiency and non-viability in animal models (Aringer, M., et al.). The JAK family of enzymes is characterized by a number of JAK homology (JH) domains, including a carboxy-terminal protein tyrosine kinase domain (JH1) and an adjacent kinase-like domain (JH2), which is thought to regulate the activity of the JH1 domain (Harpur, A. G., et al.). The four JAK isoforms transduce different signals by being associated specifically with certain cytokine receptors, and activating a subset of downstream genes. For example, JAK2 associates with cytokine receptors specific for interleukin-3 (Silvennoinen, O., et al., Proc Natl Acad Sci USA, 1993. 90(18): p. 8429-33), erythropoietin (Witthuhn, B. A., et al., Cell, 1993. 74(2): p. 227-36), granulocyte colony stimulating factor (Nicholson, S. E., et al., Proc Natl Acad Sci USA, 1994. 91(8): p. 2985-8), and growth hormone (Argetsinger, L. S., et al., Cell, 1993. 74(2): p. 237-44).
The JAK family of enzymes has become an interesting set of targets for various hematological and immunological disorders; JAK2 specifically is currently under study as a viable target for neoplastic disease, especially leukemias and lymphomas (Benekli, M., et al., Blood, 2003. 101(8): p. 2940-54; Peeters, P., et al., Blood, 1997. 90(7): p. 2535-40; Reiter, A., et al., Cancer Res, 2005. 65(7): p. 2662-7; Takemoto, S., et al., Proc Natl Acad Sci USA, 1997. 94(25): p. 13897-902) as well as solid tumors (Walz, C., et al., J Biol Chem, 2006. 281(26): p. 18177-83), and other myeloproliferative disorders such as polycythemia vera (Baxter, E. J., et al., Lancet, 2005. 365(9464): p. 1054-61; James, C., et al., Nature, 2005. 434(7037): p. 1144-8; Levine, R. L., et al., Cancer Cell, 2005. 7(4): p. 387-97; Shannon, K. and R. A. Van Etten, Cancer Cell, 2005. 7(4): p. 291-3), due to its activation of downstream effector genes involved in proliferation. JAK2 is also known to be mutated in hematologic malignancies, such that it no longer requires ligand binding to the cytokine receptor and is instead in a state of constitutive activation. This can occur through translocation between the JAK2 gene with genes encoding the ETV6, BCR or PCM1 proteins (Peeters, P., et al.; Reiter, A., et al.; Griesinger, F., et al., Genes Chromosomes Cancer, 2005. 44(3): p. 329-33; Lacronique, V., et al., Science, 1997. 278(5341): p. 1309-12) to create an oncogenic fusion protein, analogous to the BCR-ABL protein seen in chronic myelogenous leukemia. Overactivation of JAK2 can also occur through mutation of the JAK2 sequence itself; for example, the myeloproliferative disease polycythemia vera is associated with a point mutation that causes a valine-to-phenylalanine substitution at amino acid 617 (JAK2 V617F) (Walz, C., et al.). Because of its association with, and deregulation in, neoplastic and myeloproliferative disorders, small molecule JAK2 inhibitors for the treatment of human malignancies are of significant interest.
A need exists for ALK and JAK2 inhibitors for use as pharmaceutical agents.